This article is the first of two that covers the procedure for rebuilding a failed steering box on your Kubota. An earlier article has hints and tips regarding diagnosing steering box failure and is prerequisite reading before we jump into the actual repair covered in these next two tutorials.
Symptoms of Steering Box Failure
Failure of the steering box is actually a pretty common service complaint so it is a good idea to familiarize yourself with the symptoms:
- increased or very hard steering effort in either direction
- a crunching or clicking noise coming from the steering box
- steering wheel will turn then gets stuck or locks up
- steering wheel will not return to center after making a turn
- steering wheel is frozen in place and will not turn at above zero temperatures
- steering binds, jerks, locks, gets stuck then will “work” but feels loose
- oil is leaking from the sides of the steering box
- oil from the steering box is rusty or watery
Before We Get Started
This is the type of repair that the average Kubota tractor owner can undertake with relative ease. If you have a basic working knowledge of auto servicing or restoration then this repair is within grasp. Access to a clean work bench, a puller set and a selection of six-point metric sockets is also required.
Box and Column Removal
If you have not done so already, we recommend removing the steering box and column from the tractor to perform these repairs. It is possible to do the repair with the box still bolted to the top of the clutch housing, but, there is something to be said for comfort and a good solid work height.
Loosen the dash cowling where it attaches to the sides of the fuel tank. Spin the 4 bolts out of the dash where it mounts to the sides of the tank and you will see the dash then moves freely.
Slide the doughnut-shaped upper column bushing upwards to make the column easier to extract. Spraying a little WD40 on the column will make the bushing slide better. You will also need to pop off the steering wheel center cap and remove the wheel using a puller.
The drag link can be disconnected from the pitman arm using a tie rod end pickle fork. Next, remove the 4 bolts mounting the base of the steering box to the top of the clutch housing. Nearly there – but wait! The box will not come off yet because…
Staked with Dowels
The underside of the steering box is staked in place by a couple of metal dowels. You may need to insert a screwdriver between the bottom of the box and the top of the housing to work the box up and off.
You will find one female dowel on the underside of the box and one male dowel on the top of the clutch housing. The box fits tightly on these two dowels so expect to work it a little to get it to pop off the dowels – once you do the steering box and column are ready to be taken over to the bench.
Inspection and Tear Down
Now that you have the box on the workbench, it is a good time to inspect for damage, cracks or breaks on the cast portion of the box case. Also be on the lookout for signs of oil leakage.
Hairline cracks can be addressed with a little JB Weld. Broken box mounting tabs or large areas of destruction cannot be patched. Typically when the bottom of the box is blown out as a result of water freezing you will need a new bare box case – still available from Kubota but will likely be an expensive part.
Next, remove the pitman arm bolt and lock and use a puller to remove the arm from the steering box.
Inspect the Pitman Arm
Look closely for a scribed line that runs through the pitman arm and the end of the steering box sector shaft – this is an alignment mark that must be referenced when reinstalling the pitman arm – make note of it.
Sector Shaft Removal
To get at the sector shaft we remove the 4 bolts holding the end of the sector shaft end cover plate onto the steering box. Removing the cover plate will draw the sector shaft out of the steering box.
We need to get the steering column off the steering box. Remove the bushing from the top of the steering column and remove the 4 bolts holding the column post to the cast portion of the box. You will then be able to lift off the column.
Steering Box Inspection
With the column post detached from the box, grasp the steering shaft and withdraw it from the box case. Chances are the ball nut will still be attached to the shaft and will come out as a complete unit. Looking inside the box you may find any or all of these:
- loose ball bearings
- stray bits of metal chipped off the steering shaft worm
- drive teeth from the sector shaft
Take the time to inspect the ball nut assembly, steering shaft and sector shaft for wear. Order replacement parts as required.
Sector Shaft Seal
With the box now almost completely torn down for rebuild, pop out the old steering sector shaft seal with a straight blade screwdriver or small pry bar.
Lower Bearing Race
The last item to be removed from the steering box is the lower bearing race located inside the steering box where the ball nut steering shaft would sit. If you are lucky, this race will just pop out after some gentle tapping on the backside of the box. If not so lucky you will need to pry it up. You will find it a tight fit to wrangle a tool in there unless it has a small hook end on it that you can pry under the edge of that bearing race. I have been successful a few times removing this race by utilizing a common 6d (six penny) construction nail.
Using vice-grip pliers, lock onto the shaft of the nail and then use the head of the nail to pry up and under the bearing race. The nail head is thin enough to just catch the underside lip of the bearing cup yet is firm enough to allow you to pry against the floor of the steering box. Kubota does offer a service tool made specifically for this job – it costs a couple of million bucks. The nail works just fine and is a better deal we think!
Tear Down Complete
What you should have on your bench now is a completely bare, stripped down, steering box. Next steps, which we will cover in an upcoming article, are the clean up and rebuild! Proceed to How to Repair a Steering Box – Part 2 to continue.
Service Department Vic